1. Field of the Invention
The present invention relates to a disc drive device used for recording desired music information and the like on a disc or reproducing the recorded information, and more particularly, to a disc drive device provided with a mechanism for clamping a disc.
2. Description of the Related Art
In general, a disc drive device such as a CD player or a DVD recorder is equipped with a turntable, an optical pickup and a disc clamping mechanism. The turntable supports a disc and rotates the disc. The optical pickup moves in a radial direction of the disc along a board surface of the disc. The disc clamping mechanism clamps the disc so that the disc disposed on the turntable may rotate in synchronization with the rotation of the turntable.
The disc clamping mechanism has a clamp base and a clamp board. The clamp base is movably provided in a housing of the disc drive device. The clamp board is rotatably supported by the clamp base. In the disc clamping mechanism, the clamp board comes closer to/off the turntable dependent on the movement of the clamp base. When the clamp board moves in a direction that it comes closer to the turntable, the disc is rotatably clamped on the turntable by the clamp board at the central part of the disc.
In the condition where the clamp board is rotatably supported by the clamp base, the clamp board has one or more free ends in an axial direction and/or a radial direction of the clamp board. Therefore, in the condition where the clamp board is away from the turntable, the clamp board is likely to rattle at each free end thereof when receiving external vibration. As a result, there is a problem that the disc drive device might produce a big noise.
In order to resolve the above-described problem, Japanese Patent Application Laid-Open No. H10(1998)-92099 discloses a construction configured to provide a spring over a clamp board (clamper). With this construction, when the clamp board moves away from a turntable, the spring presses the clamp board from above the clamp board to be elastically retained.
Further, Japanese Patent Application Laid-Open No. S60(1985)-214455 discloses a construction configured to rotatably support a clamp board (pushing member) by a supporting member made up of magnetic materials and to incorporate a magnet into the clamp board. With this construction, in the condition where the clamp board is away from a turntable (non-clamped state), the clamp board is attracted to the supporting member by its own magnetic force.
Furthermore, Japanese Patent Application Laid-Open No. H10(1998)-283740 discloses a construction configured to support a clamp board (clamper plate) made up of plastic magnet by a clamp base (clamper arm). With this construction, when the clamp board moves away from a turntable, the clamp board is attracted to a chassis by its own magnetic force.
However, with the construction disclosed in Japanese Patent Application Laid-Open No. H10(1998)-92099, it is necessary to provide the dedicated spring used for preventing the clamp board from rattling. This increases the number of parts, which leads to higher costs. Also, this requires to incorporate the spring into the disc drive device, which increases the number of man-hours to reduce productivity. Further, this requires a large gap between a chassis and the clamp board, which has an adverse effect on the reduction in thickness of the disc drive device. Furthermore, this may cause secondary damage caused by the resonance of the spring.
Further, with the construction disclosed in Japanese Patent Application Laid-Open No. S60(1985)-214455, it is necessary to provide on the top of the clamp board a buffer member used for preventing the clamp board from directly hitting a case (housing) by the vibration of the supporting member. This increases the number of parts, which leads to higher costs. Also, there is a possibility that the magnetic force of the clamp board acting on the supporting member might reduce rotational performance of the clamp board.
Furthermore, with the construction disclosed in Japanese Patent Application Laid-Open No. H10(1998)-283740, a peripheral edge of one end of the clamp board is only attracted to the chassis. Therefore, in a case that the disc drive device is used within a vibration system such as a vehicle-mounted type, the clamp board vibrates about a part where the clamp board is attracted to the chassis as a fulcrum point. As a result, there is a possibility that the disc drive device might produce a big noise.